Turbo Pressure Can Spike at any RPM!! - Saab 9000 Bulletin Board - Saabnet.com
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Turbo Pressure Can Spike at any RPM!!
Posted by Kyle [Email] (more from Kyle) on Wed, 12 Dec 2001 13:05:41
In Reply to: I don't think so, Pete 
[Profile/Gallery]
, Wed, 12 Dec 2001 11:35:03
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Yes, the T-25 can produce high boost spike at any RPM, BUT ONLY MOMENTARILY.
You can create a pressure spike at any RPM by stabbing the throttle.
Try holding the boost at 1.1bar all the way from 2000rpms to redline (assuming you have a real boost gauge to read from).
If you FLOOR the car in third gear at 2000RPMs then the boost WILL drop off as you reach 4000rpm and beyond because the turbo cannot maintain enough volume to keep the pressure up.
This is what Tapani is talking about.
I have a '91 9000T with the t-25 turbo and an MBC.
The MBC is set up to consistently hold pressure from the wastegate until system pressure reaches +/- 1bar, and I have NEVER been able HOLD the boost at much more than 10-12psi past 3500rpms in third or fourth gear.
Also, if I stab the throttle in second gear at low RPMS, my boost gage will read as much as 20psi MOMENTARILY (and no fuel cutoff), but this is only a pressure SPIKE and is certainly not indicative of the turbos flow potential across its RPM range.
-Kyle
posted by 64.65.19...
Posts in this Thread:
- high rpm boost level, Tapani, Wed, 12 Dec 2001 03:10:25
- Direct Quote (more info):, Kyle, Wed, 12 Dec 2001 14:15:23
- Here's the link without the "Google" search attached:, Kyle, Wed, 12 Dec 2001 14:07:38
- Read the last paragraph at this page link:, Kyle, Wed, 12 Dec 2001 14:04:52
- Turbo is too small for high boost @ high RPMS., Kyle, Wed, 12 Dec 2001 10:03:34
- I don't think so either..., Alex, Wed, 12 Dec 2001 15:13:16
- I don't think so, Pete , Wed, 12 Dec 2001 11:35:03
- Re: Turbo is too small for high boost @ high RPMS., tapani, Wed, 12 Dec 2001 10:42:27
- Hence the larger turbo on the manual Aero n/m, BillJ, Wed, 12 Dec 2001 10:06:36
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